A pulse-Doppler radar system for measuring distance or speed in a motor vehicle is described in U.S. Pat. No. 6,362,777. Therein, a multiplier or a mixer is provided in the transmit path for supplying a signal having double the frequency of a reference oscillator to the transmitting antenna. Frequency doubling is carried out there in order to be able to use a reference oscillator having a lower frequency and thus more stable behavior.